One in five older adults is socially isolated from family or friends, increasing their risks for poor mental and physical health, as well as higher rates of mortality, a new study shows.

Researchers investigated several factors affecting social isolation from family and friends within a national sample of more than 1,300 older African-Americans, black Caribbeans, and whites. Study participants were 55 and older.

Overall, most elderly were connected to both family and friends (77 percent), while 11 percent were isolated from friends only, and 7 percent were isolated from family members only.

Of concern, however, were the 5 percent of elderly who were socially isolated from both family and friends, which may place them at risk for physical and mental health problems, researchers say.

Men were more likely than women to be socially isolated. Women’s lifelong investments in family and friend networks, often through their social roles as caregivers to others, suggest that they may be less likely to experience social isolation as they age. African-American, black Caribbean, and white older adults reported similar levels of social isolation from family and friends.

Further, older adults who live with family members may still report social isolation from friends, suggesting that these family members and friends have distinctive and complementary roles in terms of social isolation.

“In essence, our findings indicated that living arrangements themselves—alone or with others—were not indicative of social contact or engagement,” says lead author Linda Chatters, professor of social work and professor of public health at the University of Michigan.

Older adults with mobility impairments such as moving about in one’s home, standing for 30 minutes, or walking a long distance, were more likely to report being isolated from friends. In contrast, elderly who experienced impairments in self-care such as bathing and dressing were less likely to indicate being isolated from friends.

One explanation for these findings could be that mobility impairments lead to social isolation because they limit the ability to socialize with friends outside the home, the researchers say. In contrast, because self-care impairments reflect a higher level of physical frailty, friends may be more likely to make home visits to the elderly.